Sealing arrangement for a torque converter vane damper

ABSTRACT

A torsional isolator assembly for reducing driveline torsionals includes a vane damper (36) having valving (40d,40e or 161,163) and chamfers (200,201) on pistons (60 or 160). These chamfers (200,201) aid in forming a seal between a surface (42d or 142d) by creating a hydrodynamic film that biases the piston (60 or 160) toward the housing surface (42d or 142d).

CROSS REFERENCE

This application is related to U.S. application Ser. Nos. 07/872,860 and07/873,434, filed Apr. 23, 1992, and both assigned to the assignee ofthis application.

FIELD OF THE INVENTION

This invention relates to a hydraulic vane damper disposed in parallelwith torsion isolator springs for use in a vehicle driveline. Morespecifically, this invention relates to reducing oil leakage from thehydraulic vane damper.

BACKGROUND OF THE INVENTION

It is well-known that the speed of an Otto or Diesel cycle engine outputor crankshaft varies even during so-called steady-state operation of theengine, i.e., the shaft continuously accelerates and decelerates aboutthe averages speed of the shaft. The accelerations and decelerationsare, of course for the most part, a result of power pulses from theengine cylinders. The pulses may be of uniform frequency and amplitudewhen cylinder charge density, air/fuel ratio, and ignition are uniform.However, such uniformity does not always occur, thereby producing pulseswhich vary substantially in frequency and amplitude. Whether uniform ornot, the pulses, which are herein referred to as torsionals, aretransmitted through vehicle drivelines and to passengers in vehicles.The torsionals, which manifest themselves as vibrations, are detrimentalto drivelines and derogate passenger-ride quality. Further, when anengine is abruptly accelerated and/or decelerated by accelerator pedalmovement or other factors, torque pulses ring through the driveline andalso derogate ride quality, such pulses are herein also referred to astorsionals.

Since the inception of automobiles, many torsional isolator mechanismshave been proposed and used to isolate and dampen driveline torsionals.The isolator mechanism proposed in U.S. Pat. No. 5,078,649 includes, asdoes the isolator mechanism herein, flat, long travel spiral springsconnected in parallel with a vane damper device. Both mechanisms aredisposed in a torque converter housing and immersed in the pressurizedtorque converter oil therein. U.S. Pat. No. 5,078,649 is incorporatedherein by reference. The amount of damping (i.e., damping factor)provided by the vane damper device in this patent has been consideredmarginal in some applications due to valving arrangements employedtherewith and leakage of oil from the working chambers of the damper.The isolator mechanism disclosed herein includes features for overcomingthe above mentioned disadvantages.

SUMMARY OF THE INVENTION

An object of this invention is to provide a torsion damper device havingan improved damping factor.

According to a feature of this invention, a torsion assembly is adaptedto be disposed for rotation about an axis in a driveline torqueconverter housing filled with an incompressible torque converter fluid.The assembly is immersed in the fluid and is drivingly connected betweenfirst and second rotatably mounted drives. The assembly comprisesresilient means for transmitting driveline torque between the drives anda hydraulic coupling for damping torque fluctuations in response toflexing of the resilient means. The coupling includes first and secondrelatively rotatable housing means defining an annular chamber havingradially spaced apart cylindrical surfaces and first and second axiallyspaced apart end surfaces. The cylindrical surfaces and the first endsurfaces are defined by the first housing means. Circumferentiallyspaced apart walls are sealing fixed to the first housing means andextend radially and axially across the annular chamber for dividing theannular chamber into at least two independent arcuate chambers. A pistonis disposed in each arcuate chamber for driving each arcuate chamberinto pairs of first and second volumes which vary inversely in volume inresponse to movement of the pistons relative to the first housing means.Each piston has radially oppositely facing surfaces in sliding sealingrelation with the chamber cylindrical surfaces, has first and secondaxially oppositely facing end surfaces in sliding sealing relationrespectively with the first and second end surfaces of chamber, and hasfirst and second circumferentially spaced apart and oppositely facingsurfaces, respectively intersecting the first and second oppositelyfacing end surfaces. The second housing means includes an annularradially extending housing member having an axially facing surfacedefining the second end surface of the annular chamber. The housingmember second end surface is in sliding sealing relation with eachpiston second end surface. The housing member is in sliding sealingrelation with portions of the first housing means, is retained againstaxial movement in a direction away from the first surface of the annularchamber by means affixed to the first housing means, and includes a setof circumferentially spaced and axially extending through openings.Piston drive means connect the pistons to the first drive via a pathindependent of the resilient means. The piston drive means extendthrough the housing member openings with circumferential free playtherebetween for allowing limited to-and-fro circumferential movement ofthe pistons relative to the housing member. Housing drive means connectthe first housing means to the second drive independent of the resilientmeans. Passage means effect fluid communication of the pairs of volumeswith the fluid in the torque converter housing.

The improvement is characterized by the passage means including openingsextending through the housing member for communicating the torqueconverter fluid with each volume via first and second paths associatedrespectively with the first and second volumes. Portions of the sealingrelation between the pistons and the housings are movable to positionsblocking the first paths and unblocking the second paths in response toflexing of the resilient means in a direction tending to decrease andincrease the first and second volumes respectively. The portions aremovable to positions blocking the second paths and unblocking the firstpaths in response to the flexing tending to decrease and increase thesecond and first volumes, respectively. At least one of theintersections of each piston first and second circumferentially facingsurfaces with the piston end surface includes a chamber for promotinggeneration of a hydrodynamic film with the fluid for biasing each pistontoward the chamber second end surface and for increasing the sealingrelation between each piston second end surface and the chamber secondend surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The torsion isolator assembly of the present invention is shown in theaccompanying drawings in which:

FIG. 1 schematically illustrates a motor vehicle driveline including atorque converter type transmission employing a torque converter bypassdrive embodying the torsion isolator assembly;

FIG. 2 is a detailed sectional view of the isolator assembly lookingalong staggered section line 2--2 of FIG. 3;

FIG. 3 is a reduced size detailed sectional view of the isolatorassembly looking along staggered section line 3--3 of FIG. 2;

FIG. 4 is a sectioned view of a portion of the isolator mechanismlooking leftward in FIG. 2;

FIG. 5 is a sectional view of a modified portion of the isolatormechanism;

FIG. 6 is a reduced size detailed sectional view of an alternativeembodiment of the isolator assembly;

FIG. 7 is a sectioned view of a portion of the isolator mechanism inFIG. 6 and looking leftward as in FIG. 2;

FIG. 8 is a relief view of a piston in the isolator assembly of FIG. 6;and

FIG. 9 is a sectional view of a portion of the isolator assembly lookingalong line 9--9 of FIG. 7.

DETAILED DESCRIPTION OF THE DRAWINGS

The motor vehicle driveline seen schematically in FIG. 1 includes aninternal combustion engine 10, an automatic transmission 11 and a driveshaft 12 driving a load such as rear or front wheels 13 of a vehiclethrough a differential 14.

The transmission includes a torque converter assembly 15 having anoutput shaft 16 and a gear ratio box 18 driven by the torque converteroutput shaft 16. Torque converter assembly 15 is filled with automatictransmission fluid and includes, in known manner, an impeller 20 drivenfrom engine 10 through a torque converter housing 22, a stator 24, and aturbine 26 driven hydrokinetically by the impeller. A fluid coupling maybe employed in lieu of a torque converter.

Torque converter assembly 15 further includes a bypass driveline seengenerally at 27 in FIG. 1. Bypass driveline 27 is operative whenselectively actuated to provide a bypass drive between torque converterhousing 22 and torque converter output shaft 16 through a torsiondamping isolator assembly 30, thereby bypassing the high slippage drivepath through the torque converter.

Referring now to FIGS. 2-4, isolator assembly 30 includes a pair ofnested, flat, spiral wound springs 32,34 disposed normal to the axis ofthe assembly, and a vane type damper mechanism 36 including housingmembers 38,40 defining an annular chamber 42, and a clutch or pistonplate 44. Plate 44 includes a radially extending portion 44a having anaxially extending hub portion 44b at its center and an axially extendingflange portion 44c at its radially outer edge. An outer cylindricalsurface of hub portion 44b has an inner cylindrical surface of housingmember 38 journaled therein to maintain concentricity between the plateand housing. An inner cylindrical surface of hub portion 44b cooperateswith an o-ring seal 46 carried in an annular recess in an outer surfaceof an adapter 48. The adapter is affixed to torque converter turbine 26and includes internal splines 48a for mating with splines on shaft 16and external splines 48b for slidably mating with splines on housingmember 38.

During non-bypass operation of the torque converter, pressurizedtransmission oil is admitted to the torque converter via a chamber 50receiving the oil through passages in shaft 16 in known manner. The oilin chamber 50 prevents frictional engagement of plate 44 with a frictionlining 52 affixed to the shown portion of torque converter housing 22.The oil thus flows radially outward in chamber 50 past lining 52 andinto the torque converter via a main torque converter chamber 54separated from chamber 50 by plate 44. When it is desired to engage theisolator assembly, as for example, when the vehicle is operating in ahigher gear ratio and above a predetermined vehicle speed, the directionof flow of the pressurized oil is reversed by actuation of a suitablevalve, not shown. Specifically, the pressurized oil is now admittedfirst to chamber 54 where it acts against the radially extending portion44a of plate 44 and slides the entire isolator assembly to the left tofrictionally engage lining 52. Driveline torque now bypasses the torqueconverter and is transmitted to shaft 16 by spiral springs 32,34 whichflex to attenuate torsionals in the torque. Damper assembly controls therate of flexing of the springs.

Annular chamber 42 includes radially spaced apart cylindrical surfaces42a,42b defined by axially extending annular wall portions 38a,38b ofhousing member 38, and axially spaced apart end surfaces 42c,42drespectively defined by a radially extending portion 38c of housingmember 38 and housing member 40. Annular chamber 42 is divided intothree arcuate chambers 56 sealed from each other by fixed vanes or walls58. The walls are press fit into grooves in wall portions 38a,38b,38cand extend radially and axially across the annular chamber. The radiallyouter extent of axially extending wall portion 38a includes a radiallyoutwardly extending flange 38f and a pair of scroll or spiral shaped padportions 38g to reduce bending stress concentration in the innerconvolutions of the springs when they decrease in overall diameter dueto transmission of torque in the positive direction of arrow A.

Each arcuate chamber 56 is divided into pairs of variable volumechambers 56a,56b by moveable vanes or pistons 60. Pistons 60 are eachseparate members but may be affixed together in a manner similar to thatin U.S. Pat. No. 4,768,637, which patent is incorporated herein byreference. Each piston 60 includes radially outer and inner surfaces60a,60b in sliding sealing relation with housing member cylindricalsurfaces 42a,42b, an axially facing end surface 60c in sliding sealingrelation with housing end surface 42c, and an axially facing end surface60d in sliding sealing relation with end surface 42d of housing member40. Axial spacing of piston end surfaces 60c,60d between end surfaces42c,42d of the chamber and between surface 42d and the adjacent ends ofwalls 38a,38b is controlled and maintained by an annular shim 62sandwiched between housing member 40 and a radially inner portion 64a ofan annular flange 64. Flange 64 abuts the free axial end of housing wallportion 38a and is affixed to housing member 38 by appropriatefasteners, such as by two sets of three fasteners 65 which extendthrough openings in flange 64, openings in pad portion 38g, and openingsin flange portions 38f. A radially outer portion 64b of flange 64includes through openings 64c spaced one hundred-eighty degrees apartand in axial alignment with openings 38h in flange portions 38f.

Housing member 40 includes outer and inner circumferential surfaces40a,40b in sliding sealing relation with cylindrical wall surfaces42a,42b, and three circumferentially spaced apart through openings 40cwhich loosely receive round pin lugs 66 fixed at one end to clutch plate44 and at the other end are slidably received in recesses 60e in thepistons. Since pistons 60 are separate members, lugs 66 position and fixthe circumferential spacing of the pistons relative to each other. Theview of housing member 40 in FIG. 4 is looking leftward in the directionof surface 42d thereof with pin lugs 66 in section and pistons 60superimposed on surface 42d in phantom lines.

Pistons 60 each include circumferentially oppositely facing surfaces60f,60g which cooperate with three pairs of restricted passages 40d,40eextending axially through housing member 40 for communication ofpressurized makeup oil from torque converter chamber 54 into variablevolume chambers 56a,56b. Each pair of passages are circumferentiallyspaced apart a sufficient distance determined by the circumferentialspacing of piston surfaces 60f,60g, and the amount of circumferentialfree play between pin lugs 66 and through openings 40c. Thecircumferential free play allows sufficient limited circumferentialmovement of the pistons relative to housing member 40 for piston endsurfaces 60d to close or block the passages associated with variablevolume chambers which, at any given time, are decreasing in volume, andfor the piston end surfaces 60d to move to positions opening orunblocking the passages associated with variable volume chambers which,at any given time, are increasing in volume.

In vane damper 36, as thus far described, pin lugs 66 are received inpiston recesses 60e with little or no clearance therebetween.Alternatively, pin lugs 66 and piston recesses 60e may have additionalclearance or free play therebetween so as to provide a lost motionbetween piston plate 44 and pins 66 for providing a non-hydraulicdamping zone of 1 or 2 or more rotational degrees. Herein, as shown inFIG. 5, the clearance is provided by reducing the diameter of a portion66a of the pin lugs received in piston recesses 60e.

Restricted passages 40d,40e in housing member 40 may be made larger thanshown herein to allow a greater rate of oil flow therethrough and/or toallow forming of the passages by a low cost punching process rather thanby drilling. If the enlarged passages are wider in the circumferentialdirection of movement of pistons 60, the circumferential free playbetween pin lugs 66 and housing member through openings 40c should beincreased to ensure sufficient relative rotation of pistons 60 relativeto housing member 40 to provide complete opening and closing of thepassages by piston end faces 60d.

Spring convolutions 32,34 respectively include radially outer ends32a,34a and radially inner ends 32b,34b. The ends may be attached in anyof several known ways, e.g., such as disclosed in previously mentionedU.S. Pat. No. 5,078,649. Herein it should suffice to say that outer ends32a,34a are pivotally secured to the radially outer extent of clutchplate 44 by pins 68 and brackets 70, and with the pins locked in placeby unshown split pins in known manner. The inner ends 32b,34b of thesprings are secured to housing member 38 by pins 72 extending throughaxially aligned openings 64c,38h and are locked in place in the samemanner as pins 68. When the springs are transmitting positive torque andtending to wind up, pivotal movement of the spring ends 32b,34b islimited by scroll pads 38g. When the springs are transmitting negativetorque or being acted on by centrifugal forces and therefore tending tounwind or expand radially outward, pins 72 allow free pivotal movementof spring inner ends 32 b,34b. Herein, maximum wind-up or unwinding ofthe spiral spring convolutions is limited by engagement of pistonsurfaces 60f,60g with walls 58. By way of example, wind-up is limited to+52 degrees and unwinding is limited to -25 degrees. The springs areshown in the relaxed state in FIG. 3.

FIGS. 6-9 illustrate an alternative embodiment for controlling supply ofmakeup fluid to variable volumes 56a,56b and the addition of chamfers onedges of the pistons for promoting generation of a hydrodynamic film atone end of each piston. Elements in FIGS. 6-8 which are substantiallythe same as in FIGS. 2-4 have the same reference number with a "1"prefix.

Housing member 140 includes outer and inner circumferential surfaces140a,140b and three circumferentially spaced apart elongated throughopenings 141 which loosely receive round pin lugs 166 fixed at one endto the clutch plate and at the other end are slidably received inrecesses 160e in the pistons. Openings 141 may be round as in FIGS. 2-4.

Pistons 160 each include circumferentially oppositely facing surfaces160f,160g and porting recesses 161,163 for directing pressurized makeupoil from the torque converter chamber into variable volume chambers156a,156b. The porting recesses extend circumferentially in oppositedirections from an inlet end 161a,163a thereof to an outlet end thereofin direct communication with variable volume chambers 156a,156b. Thecircumferential free play between pin lugs 166 and through openings 141allows limited circumferential movement of the pistons relative housingmember 140 for surface 142d to sealingly cover one set of the portingrecess and uncover the inlet ends of the other set in response to torquein either direction. Each inlet 161a,163a is spaced from the pin lugs166 or piston pin lug recesses 160e by portions of piston surface 160dwhich cooperate with portions of housing member surface 142d to seal theinlets from communication with makeup oil via the openings 141. As seenin FIG. 9, porting recess inlets 163a are sealingly 14 covered byhousing member surface 142d , and porting recess inlets 161a areuncovered and open into housing member openings 141 when torquetransmission is in a direction tending to decrease volumes 156a andincrease volumes 156b, thereby sealing volumes 156a from communicationwith the pressurized oil in torque converter chamber via portingrecesses 161 and communicating the pressurized makeup oil to volumes156b via recesses 163a. FIG. 7, which is viewed in a direction oppositethe direction of FIG. 6, illustrates the position of the pistons andhousing member 140 when torque transmission is in a direction tending todecrease volumes 156b and increase volumes 156a. Pistons 160 arepreferably formed in known manner of compacted powered metal with pistonpin recesses 160e and porting recesses 161,162 being formed during thecompacting process.

As may be seen by reference to FIG. 9, the intersections of the pistoncircumferentially facing surfaces 160f,160g with piston end surface 160care provided with chamfers 200,201 to promote generation of ahydrodynamic fluid film between piston end surface 160c and chambersurface 142c. The chamfering feature, of course, may be employed in theembodiment for FIGS. 2-4. The fluid film biases the piston towardchamber surface 142d, thereby improving the sealing relation betweenchamber surface 142d and piston end surfaces 160d for reducing leakageof fluid therealong from the variable volume chambers tending todecrease in volume (i.e., the chambers having fluid at relatively highpressure) to openings 141, and with reference to FIG. 2 to also reduceleakage across the interface of shim 62 with flange 64 and housingmember 40. The angle ⊖ of chamfer surfaces 200,201 is shownsubstantially greater than need be in practice. For example,satisfactory test results have been obtained with angles of about fivedegrees and openings X provided by the chambers of about 0.4millimeters. Further, both intersections need not be chamfered ifimproved sealing is required in only one direction. Also, the chamfersneed not extend the full length of the intersection and the chamfersneed not be flat surfaces (i.e., the chamfers may be formed by roundingthe intersections).

While the embodiments of the present invention have been illustrated anddescribed in detail, it will be apparent that various changes andmodifications may be made in the disclosed embodiments without departingfrom the scope or spirit of the invention. The appended claims areintended to cover these and other modifications believed to be withinthe spirit of the invention.

What is claimed is:
 1. A torsion isolator assembly adapted to bedisposed for rotation about an axis in a driveline torque converterhousing filled with an incompressible torque converter fluid, theassembly immersed in the fluid and drivingly connected between first andsecond rotatably mounted drives; the assembly comprising resilient meansfor transmitting driveline torque between the drives and a hydrauliccoupling for damping torque fluctuations in response to flexing of theresilient means; the coupling including first and second relativelyrotatable housing means defining an annular chamber having radiallyspaced apart cylindrical surfaces and first and second axially spacedapart end surfaces, the cylindrical surfaces and the first end surfacedefined by the first housing means, and circumferentially spaced apartwalls sealingly fixed to the first housing means and extending radiallyand axially across the annular chamber for dividing the annular chamberinto at least two independent arcuate chambers; a piston disposed ineach arcuate chamber for dividing each arcuate chamber into pairs offirst and second volumes which vary inversely in volume in response tomovement of the pistons relative to the first housing means; each pistonhaving radially oppositely facing surfaces in sliding sealing relationwith the chamber cylindrical surfaces, having first and second axiallyoppositely facing end surfaces in sliding sealing relation respectivelywith the first and second end surfaces of the chamber, and having firstand second circumferentially spaced apart and oppositely facing surfacesrespectively intersecting the first and second oppositely facing endsurfaces; the second housing means including an annular radiallyextending housing member having an axially facing surface defining thesecond end surface of the annular chamber, the second end surface beingin sliding sealing relation with each piston second end surface, thehousing member being in sliding sealing relation with portions of thefirst housing means and retained against axial movement in a directionaway from the first end surface of the annular chamber by means affixedto the first housing means, and the housing member having a set ofcircumferentially spaced and axially extending through openings; pistondrive means for connecting the pistons to the first drive via a pathindependent of the resilient means, the piston drive means extendingthrough the housing member openings with circumferential free playtherebetween for allowing limited to-and-fro circumferential movement ofthe pistons relative to the housing member; housing drive means forconnecting the first housing means to the second drive independent ofthe resilient means; and passage means for effecting fluid communicationof the pairs of volumes with the fluid in the torque converter housing;characterized by:the passage means including fluid passages extendingthrough the housing member for communicating the torque converter fluidwith each volume via first and second paths associated respectively withthe first and second volumes, portions of the sealing relation betweenthe pistons and the housing movable to positions blocking the firstpaths and unblocking the second paths in response to flexing of theresilient means in a direction tending to decrease and increase thefirst and second volumes respectively, and the portions movable topositions blocking the second paths and unblocking the first paths inresponse to the flexing tending to decrease and increase the second andfirst volumes, respectively; and at least one of the intersections ofeach piston first and second circumferentially facing surfaces with thepiston end surface including a chamfer for promoting generation of ahydrodynamic film with the fluid for biasing each piston toward thechamber second end surface and for increasing the sealing relationbetween each piston second end surface and the chamber second endsurface.
 2. The torsion isolator assembly of claim 1, wherein:both ofsaid intersections include said chamfer for promoting the generation ofthe hydrodynamic film.
 3. The torsion isolator assembly of claim 1,wherein:the fluid passages of the passage means include a first and asecond passage respectively being the first and second paths andassociated with each piston for respectively communicating the first andsecond volumes with the fluid in the torque converter housing, the firstand second passages respectively blocked and unblocked by the second endsurface of the associated piston in response to said flexing in adirection tending to decrease the first volumes, and the second andfirst passages respectively blocked and unblocked by the second endsurface of the associated piston in response to said flexing in adirection tending to decrease the second volumes.
 4. The torsionisolator assembly of claim 3, wherein:the resilient means comprises atleast two flat spiral wound springs having nested spiral convolutions,each convolution including a radially outer end secured to the pistondrive means and a radially inner end secured to the first housing means.5. The torsion isolator assembly of claim 3, wherein:both of saidintersections include said chamfer for promoting the generation of thehydrodynamic film.
 6. The torsion isolator assembly of claim 1,wherein:the fluid passages of the passage means are defined by thehousing member openings and the first and second paths include first andsecond recesses in each piston second end surface and respectivelyextending circumferentially in opposite directions from an inlet thereofspaced from the drive means by a portion of the piston second endsurface and to positions respectively communicating with the first andsecond volumes, each first recess inlet sealingly covered by the housingmember second end surface and each second recess inlet opening into theassociated housing member opening in response to movement of the pistonsin a direction tending to decrease the first volumes, therebyrespectively sealing the first volumes from communication with fluid inthe torque converter housing via the first recesses and communicatingthe second volumes with fluid in the torque converter housing via thesecond recesses, and each second recess inlet sealingly covered by thehousing member second end surface and each first recess inlet openinginto the associated housing member opening in response to movement ofthe pistons in a direction tending to decrease the second volumes,thereby respectively sealing the second volumes from communication withfluid in the torque converter housing via the second recesses andcommunicating the first volumes with fluid in the torque converterhousing via the first recesses.
 7. The torsion isolator assembly ofclaim 6, wherein:the resilient means comprises at least two flat spiralwound springs having nested spiral convolutions, each convolutionincluding a radially outer end secured to the piston drive means and aradially inner end secured to the first housing means.
 8. The torsionisolator assembly of claim 6, wherein:both of said intersections includesaid chamfer for promoting the generation of the hydrodynamic film.